Stitching apparatus



1965 T. c. ZINNIGER STITCHING APPARATUS 4 Sheets-Sheet 2 Original FiledFeb. 28, 1965 INVENTOR. THEODORE C ZINN|GER BY 4 Sheets-Sheet 3 I I ]3 BINVENTOR.

THEODORE C ZINNIGE Dec. 14, 1965 T. c. ZINNIGER smcnme APPARATUSOriginal Filed Feb. 28, 1963 Dec. 14, 1965 'r. c. ZINNIGER 3,222,779

STITCHING APPARATUS vOriginal Filed Feb. 28, 1963 4 Sheets-Sheet 4INVENTOR.

THEODORE C Zl NNIGER United States Patent 10 Claims. (Cl. 29-566) Thisapplication also constitutes a division of my prior application SerialNo. 261,648, filed February 28, 1963.

This invention relates to an apparatus for joining together overlappedpieces of material by means of fastener elements formed integrally withthe respective pieces of material, as well as the fastener elementsformed thereby.

Accordingly, it is a primary purpose of this invention to provide anovel apparatus for fastening together a plurality of sheets ofmaterial, such as metal sheets, Without the use of additional orexternal fastening elements, as well as a novel fastening element formedas an integral part of the pieces of material being fastened together.

Other purposes and advantages of the instant invention will become moreapparent by reference to the following detailed description when takenin conjunction with the appended drawings, wherein FIG. 1 is a brokenplan view of a fastener made in accordance with prior art practices;

FIG. 1a is a cross-sectional view of the fastener shown in FIG. 1 Whentaken generally along the line la-la thereof;

FIG. lb is a cross-sectional view of the fastener shown in FIG. 1 whentaken generally along the line 1b]lb thereof;

FIG. 2 is a broken plan view of the novel fastener of the instantinvention and indicates how a plurality of such fasteners may beemployed in the form of a pattern to join pieces of material together;this figure also discloses in phantom certain trigonometricalcalculations or concepts used in arriving at the preferred configurationfor the fastener of the instant invention;

FIG. 3 is a cross-sectional view of a fastener shown in FIG. 2 whentaken generally along the line 3-3 thereof;

FIG. 4 is a cross-sectional view of a fastener shown in FIG. 2 whentaken generally along the line 4-4 thereof;

FIG. 5 is an exploded perspective view of a suitable punch and dieapparatus for use in practicing the instant invention;

FIG. 6 is a plan view of the punch portion of the apparatus shown inFIG. 5 when taken generally along the line 66 of FIG. 7;

FIGS. 7, 8 and 9 are partial sectional ,VieWs of the punch and dieapparatus of FIG. 5 used to practice the instant invention and disclosescertain of the steps that can be employed in producing a fastenerelement of the instant invention;

FIG. 10 is a perspective view of a modified form of fastener of theinstant invention;

FIG. 11 is a sectional view generally taken along the line 11-11 of FIG.10;

FIG. 12 is a sectional view with parts broken away of a modified punchand die apparatus that can be advantageously used to practice theinstant invention; and

FIG. 13 is a fragmentary view of a fastener of the instant invention anddiscloses schematically how a shear load applied thereto is broken downinto various components.

With further reference to the drawings, and in particular FIGS. 1through 4, 10 and 11, the improved novel fastener of the instantinvention is intended to overcome certain of the deficiencies whichexisted in prior art fasteners of the type shown in FIGS. 1 through 112,such as the 3,222,779 Patented Dec. 14, 1965 fasteners disclosed in US.Patents 2,254,558 and 2,924,- 312 issued September 2, 1941, and February9, 1960, respectively, to I. A. Williams.

In the case of a prior art fastener of the type shown in FIGS. 1 through1b, the spaced and parallel fold areas 2 and 4 at the side edges of thefastener constituted the weakest areas of the fastener. These fold lines2 and 4 were located parallel to each other and at substantially rightangles to the main parallel incisions or cuts 5 and 6 in the pieces ofsheet material, such as metal sheets S and S from which the fastener wasmade. In general, the prior art fasteners contemplated that thecomposite metal web W of the fastener located between the folds 2 and 4and incisions 5 and 6 and made up of integral parts of sheets S and Swould be displaced out of the normal planes of the sheets S and S to aplane below the bottom surface 7 of the lowermost sheet of material SAfter being displaced to a point below bottom surface 7, composite web Wwas then spread laterally outward adjacent the incisions 5 and 6, suchas in the areas 8 and 9, below the bottom surface 7 of the lowermostsheet S and into engagement with surface 7 So as to preventdisengagement of the members S and S from each other. Fold lines 2 and 4are formed in the fastener 1 as the web W is displaced. These fold lines2 and 4, however, represented the weakest parts of such a fastener inthat they did not satisfactorily withstand severe shearing actionapplied to the joined pieces of material. By shearing action is meantthe sliding action of the sheets S and S and folds 2 and 4 in thefastener 11. of the sheets S and S with respect to one another in thedirection of either of the arrows AA when opposing portions of thesheets S and S were subjected to a tensile pull in a direction normal tothe incisions 5 and 6 and parallel to fold lines 2 and 4. When thistensile pull is exerted in the direction of either of the arrows AA ofFIG. 1, the fastener would tend to come apart as the material at thefold lines 2 and 4 of the pieces S and S of material fractured under theloads imposed thereon.

It has been found, however, that this Weakness problem in such fastenerscan be solved if the fasteners of FIGS. l-lb are given a uniqueconfiguration. This unique configuration is preferably a trapeziformconfiguration.

Thus, the unique fastener element 1a of the instant invention is so madewhereby it generally comprises integral portions of overlapping piecesof material which are displaced out of the respective normal planes ofthe said pieces of material. As indicated in FIG. 2, each of the piecesof displaced material is generally defined by a pair of laterallyspaced-apart incisions 5 and 6' in the pieces, said incisions beingpreferably arranged parallel to each other, and a pair of preferablyspaced-apart folds 2' and 4' in the pieces, said folds being arranged inangularly disposed converging relationship to each other. Each of thefolds 2 and 4' also fully intersects with each of the laterallyspaced-apart incisions 5 and 6' in the pieces such that one of theinterior angles X of intersection is less than while the other interiorangle Y of intersection is greater than 90. Portions of each displacedpiece of material adjacent at least one of the incisions is displacedcompletely below and underlies the bottom surface of the lowermost pieceof material. In an advantageous embodiment of the invent-ion the portionof the fastener adjacent the other incision can be comprised of portionsof each piece of material which are displaced only below the bottomsurface of an upper piece of material being joined by the fastener.

In the case of the fastener 1 shown in FIGS. 1-1b, this fastener iscapable of transmitting its maximum load when it is designed to fail inshear along the fold lines 2 and 4- or when shear loads are applied inthe direction of the arrows A-A. When, however, these fold lines arearranged or oriented in converging fashion or on diagonals in the mannershown in FIG. 2, the overall shear area of the new folds 2' and 4' offastener 1a is substantially increased. This can be graphicallyillustrated in the following manner, reference being made to FIGS. 1 and2. In the case of the fastener of FIGS. 1-11), the distance L for eachof the fold lines 2 and 4, each fold line also being at a right angle tothe incision lines and 6, is the same. For the configuration of thefastener 1 as shown in FIG. 1, the shear area for either of the folds 2and 4 is readily calculated at Lt, t being the combined thicknesses ofthe individual pieces of material in each fold line 2 or 4, and L, ofcourse, being the length of the same.

Sloping each of the fold lines 2' and 4' in the manner indicated in FIG.2 for new fastener 1a automatically increases the shear area of each ofthe new fold lines 2' and 4' of fastener 1a, as compared to fold lines 2and 4 of fastener 1. The reason for this is illustrated by thetheoretical right triangle shown schmatically and superimposed partiallyon the fastener 1a in FIG. 2. This triangle is formed by old fold line 2of fastener 1, the new fold line 2' of fastener 1a and the base linerepresented by the reference numeral 3 as an extension of incision 6'.In forming such a triangle, it is assumed that incisions 5 and 6' offastener 1a in FIG. 2 are located the same distance apart as incisionlines 5 and 6 of fastener 1. In the aforesaid triangle, new fold line 2thus becomes the hypotenuse of the triangle and, consequently, is longerthan old fold line 2. Trigonometrically, therefore, the shear area of anew fold line 2' or 4' increases by the reciprocal of the sine of theangle 5 of the above right triangle. Thus, whereas the shear area foreither fold line 2 or 4 in the case of the fastener 1 of FIG. 1 issimply Lt, the shear area of either of the fold lines 2' or 4' in thefastener 1a of FIG. 2 is Lgtz, L being fastener 1a of FIG. 2 is L t Lbeing the length of either of the fold lines 2' or 4 and t being thecombined thickness of the individual pieces of material in each of thenew fold lines 2' and 4'. Since L equals Lt; sine In addition toincreasing the shear area, sloping of the sides or folds 2' and 4' ofthe fastener 1a decreases the shear loads on each of the folds. This isillustrated graphically in the triangulation or diagram of forcessuperimposed upon the fastener element 1a shown in FIG. 13. FIG. 13indicates that the applied load F which is applied in a directionparallel to that of a fold line 4 of a fastener 1 and normal to theincisions 5' and 6 automatically breaks down in the case of fastener 1ainto components parallel and normal to diagonally disposed fold line 4'of fastener 1a, such as components C and S. Component C represents theportion of the load F which is applied in the form of a compressive loadon the new fold line 4' of fastener 111, while the component S whichparallels new fold 4' of fastener 1a represents the portion of the loadF which is applied in the form of a shear load.

In the case of fastener 1a, therefore, the shear load S is always lessthan the applied load F because in the right triangle of forces formedby C, S and F, F becomes the hypotenuse of the triangle; and S being oneof the sides of the triangle, it must always be less than F. From theabove, it follows that the shear load S per unit area of a diagonallydisposed fold line 4' of fastener 1a in the above example willnecessarily be less than in the case of where the applied load F is notbroken down into separate shear and compressive components but remainsas a single load applied along the length of and parallel to a foldline, such as fold line 4 of a prior art fastener 1. In the aboveexample, it is also assumed that incision lines 5' and 6' of fastener 1aare located the same distance apart as incision lines 5 and 6 of a priorart fastener 1.

In a further advantageous embodiment, and as indicated in FIGS. 10 and ll, the fastener 1a of the instant invention can be made in such a waythat the integral portions of the pieces of material S and S that aredisplaced out of the normal planes of the respective pieces of materialin the form of the composite web W would be so displaced that thefastener would have a tapered configuration in a plane normal to theincisions 5 and 6, such as in the plane H of FIG. 11, and only a portion9 of the fastener la adjacent one of the incision lines would be locatedcompletely below the bottom surface 7' of the lowermost sheet S andthereafter spread underneath this bottom surface in the area D with theportion of the fastener displaced along the other shear line having onlya partial thickness C located below the bottom surface of the lowermostsheet S By making the fastener in this way, the high unit loading at thepoint M by loads applied in the direction of the arrow N is lessenedsince the bearing area between the different thicknesses of material isincreased simply by sloping the pierced segment or composite web W.

With further reference to the drawings, and in particular FIGS. 5through 9, one form of novel apparatus that can be used for fabricatingthe fasteners 1a of the instant invention generally comprises acooperating punch and die 20 and 22. The die 22 is provided with a shankor body section 24-, the lower portion of which is threaded so that itcan be conveniently afiixed to a conventional tool holder. Projectingupwardly from the body portion 24 is at least one and preferably aplurality of anvils 26a and 26b which can advantageously be madeintegral with the body portion 24. These anvil elements 26a and 26b canbe advantageously curved at their free extremities such that each oftheir free extremities has a generally arcuate work-engaging surface 28,which in a preferred form of the invention is also tapered in adirection normal to the arc of a surface 28. When the anvil elements 26aand 26b are curved in this fashion, the web W of fastener 1a will beslightly curved from fold line 2 to fold line 4 in the manner shown indotted lines in FIG. 4. A spindle 32 is disposed in suitable apertures32a in the anvils 26a and 26b. Mounted on spindle 32 and ininterdigitated relationship with the anvil elements 26a and 26b is oneor more working cutter elements 34, 34a and 34b. These cutter elementsare preferably shaped somewhat like washer elements. The die assembly iscompleted by means of additional non-working cutter elements 34c and 34dmounted upon the extremities of spindle 32, a pair of helical springs 38interposed between cutter elements 34b and 34d, 34a and 34c, and screwand washer means 40 afiixed to the opposing ends of the spindle 32.Cutter elements 34c and 34d can thus serve as washer-like anchoringelements, as well as reserve cutter elements when not in use.

The helical spring elements 38 advantageously bias the outermost workingcutter elements 34a and 3419 against the sides of anvils 26a and 26b.The innermost cutter element 34 is of such a width that it fits snuglyin the space 37 between the upwardly projecting anvils 26a and 26b. Itis contemplated in the case of the outermost spring'biased workingcutter elements 34a and 34b that these cutters would be displacedslightly from their abutting relationship with respect to the anvilmembers 2611 and 26b at the end of the fastener-forming operationwhereby the portion of the fastener adjacent at least one of theincisions 5 or 6', as indicated in FIGS. 10 and 11, can be displacedbeneath the bottom surface of the lowermost sheet S of the overlappingsheets and be projected or spread thereunder into contact with thebottom surface 7 as the punch 20 reaches the bottom of its stroke, asindicated in FIG. 9, in forming a fastener 1a, as shown in FIGS. 10 and11. For this reason, the central openings 42 in the cutters 34a, 34b,34c and 34d are purposely 5 made sufiiciently larger than the peripheryof spindle 32 whereby the cutters can be slightly rocked on and looselyheld on the spindle 32 during the bottoming of punch 20.

The punch 20 of the apparatus, as indicated in FIGS. 5 through 9, iscomprised of at least one and preferably a pair of cutter elements 50and 52 located in alignment with anvils 26a and 26b of the die 22. Thesecutter elements are removably fastened by a pin 20' to an arbor 54 whichcan be suitably secured to a moving part of the press (not shown), suchthat the punch 20 can be given the requisite upward and downwardmovement relative to the die 22. Cutters 50 and 52 are each providedwith a preferably arcuate work-engaging surface 56, which is alsopreferably tapered in a plane P or in a direction normal to the arc ofthe surface 56 in such a fashion that the work-engaging surfaces 56 ofthe cutters 5t and 52 will properly mate with the arcuate and taperedworkengaging surfaces 28 on the anvils 26a and 26b. The pposing sideedges 60 and 61 of the cutter elements 50 and 52 are also advantageouslytapered or sloped. This tapering of the side edges 60 and 61 of eachcutter element 50 and 52 occurs in planes P which are generally normalto the main plane P of taper of the curved or arcuate working surfaces56 of the cutters 50 and 52. These side edges 60 and 61 act to form theconverging side folds 2 and 4 of the plurality of fasteners In that canbe simultaneously made by the apparatus shown in FIGS. 5-9 of thedrawings. It is to be observed that the working cutter elements 34, 34aand 34b are of such a cross-sectional dimension that they are out ofbearing contact with the main shank or body portion 24 of the die 20whereby all stresses and loads imposed upon the die 20 are transferredprimarily into the anvils 26a and 26b and then through these anvils intothe shank portion 24 of the die 22. This tends to stabilize the dieportion of the apparatus in a very etficient fashion during operation.If desired, the tips 100 of the cutters 5t) and 52 can be somewhatleveled off.

In the operation of an apparatus, such as that shown in FIGS. 59,overlying pieces of material, such as metal pieces S and S are placedbetween the punch 20 and the die 22. The punch is then moved downwardlyor relative to die 22 in such a fashion that the work-engaging surfaces56 of the punch 20 pierce both of the overlapping pieces S and S ofmaterial. As the pieces S and S of material are pierced, integralportions are struck out from each of the pieces of material S and S anda displacement of the composite fastener web W formed from integralparts of the pieces of material S and S takes place along the incisionlines 5 and 6' and the fold lines 2' and 4. In this connection, it willbe observed, reference being made particularly to FIG. 6, that thecutters 50 and 52 of the punch 20 are preferably tapered in a pluralityof planes. First of all, there is a tapering of the surfaces 56 of thepunch 20 in the plane P which is normal to the work-engaging surfaces56, such that the main body or web W of the fastener will have a slopeor taper of the type shown in FIGS. 10 and 11. Secondly, the edges 60and 61 of the cutters 50 and 52 are also tapered in the planes P whichare normal to the main plane P in order to locate the fold line 2' and 4of the fastener 1a in a converging fashion relative to each other. Asthe punch moves downwardly, therefore, as indicated in FIGS. 8 and 9, iteffects a predetermined displacement of the integral portions of theoverlapping sheets forming composite web W out of the respective planesof the pieces of material from which the said integral portions areformed. This displacement action of the punch 20 continues until thefastener is fully displaced in the manner desired.

In general, it can be said that during the preferred forming of afastener 1a of the instant invention, the portions or pieces of materialconstituting the composite main body or web W of a fastener are firstsevered from the overlapping sheets S and S along incision lines 5 and 6which are preferably parallel and spaced equidistant apart along theirlength. Thereafter, the composite web W is displaced along both theincision lines 5 and 6 and along the spaced converging fold lines 2' and4'. Each of the spaced converging lines 2 and 4' also fully intersectswith the incision lines 5' and 6. The composite web W is displaced fromthe normal planes of the sheets S and S from which composite web W ismade under the action of the punch 20 until at least a part of thedisplaced web W adjacent one of the incisions 5' or 6' is firstcompletely located below the bottom surface 7 of the lowermost piece ofmaterial S being joined and thereafter spread against the said bottomsurface 7'.

FIG. 12 discloses a modified form of punch and die apparatus that can beused in practicing the instant invention. In the punch and die apparatusof FIG, 12, means are provided whereby the die can be simply adjusted soas to accommodate itself and the overall apparatus to varying gauges orthicknesses in the overlapping sheets of material S and S being workedupon by the punch 21' and die 22 to form a fastener of the instantinvention. In this instance, therefore, the punch 21' can have the samegeneral structure as that shown in FIGS. 5-9. The die 22', however, inaddition to having a body portion 24 is provided with a bore 25' withinwhich is disposed the stem 26' of the head 27' of the die 22. The head27' is provided with upstanding anvil members 26a and 26b. A pin 32' isused to anchor the plurality of cutters 7t 71, 72 and 73 to the anvilmembers 26a and 26b in interdigitated relationship. Cutters 70, 71, 72and 73 are biased against the anvils 26a and 2612 by means ofconventional disc springs 75. It is to be understood that when the die22 of FIG. 12 is used the anvils 26a and 26b of die 22' will be alignedwith the cutters 50 and 52 of the punch 21.

For the purposes of adjusting the die 22' relative to a punch 21 inaccordance with the gauges of the pieces S and S of material beingworked on, an advantageous embodiment of the invention contemplates thatthe head portion 27 will be moved relative to body portion 24 and heldin a removably adjusted position by one or more shim elements 80. Shimelements can be made of spring steel and have a U-shaped configurationwhereby they can be easily snapped about stem member 26 and at the sametime interposed between the shoulder 81 of die body portion 24 and thearms 82 of the head portion 27'. Shims 80 in effect act as stops andabutments after the height of die 22' has been adjusted with respect toits associated punch 21. For the purpose of holding the shims 80 inplace, an advantageous embodiment of the invention contemplates thatthreaded pin members 82 and 83 may be used. Pin members 82 arethreadedly affixed to head portion 27' of the die 22' while pin members83 are threadedly affixed to the body portion 24' of the die 22'. When atension spring 85 is wrapped about a pair of opposing pin members 82 and83, the head member 27' will be resiliently biased against one or moreshim or stop members 80 and thus lock or anchor the shim members inplace. A slight upward movement of head portion 27 by means of asuitable tool will allow the removal or addition of whatever shimmembers 80 are required for a particular fastener-forming operation.

Advantageous embodiments of the invention have been herein disclosed anddescribed. It is obvious that the various changes and modifications maybe made therein without departing from the spirit and scope thereof, asdefined in the appended claims, wherein What is claimed is:

1. In an apparatus for joining overlapping pieces of material togetherthe combination of a die and a punch, said die including an anvil and atleast one cutter element biased against said anvil, said anvil beingprovided with a work-engaging surface, said punch also having a cutterelement cooperatively associated with the cutter element of the die andaligned with the said anvil on said die, the cutter element on the punchbeing provided with a work-engaging surface which matches theconfiguration of the work-engaging surface on the anvil and the sideedges of the cutter element on the punch being angularly disposed inplanes normal to the Work-engaging surface of said last-mentioned cutterelement whereby as the punch and die are closed about overlapping piecesof material a portion of each piece of material Will be displaced out ofthe respective normal planes thereof to effect a joint therebetween.

2. An apparatus as set forth in claim 1 wherein the Work-engagingsurfaces of the anvil on the die and of the cutter element on the punchhave cooperating arcuate configurated portions.

3. An apparatus as set forth in claim 1 wherein the work-engagingsurface of the cutter element on said punch and the work-engagingsurface of the anvil on said die are tapered in planes normal to saidWork-engaging surfaces.

4. An apparatus as set forth in claim 1 including means for adjustingthe operating position of the anvil of said die with respect to thecutter element of the punch.

5. In an apparatus for joining overlapping pieces of material togetherthe combination of a die and a punch, said die including an anvil and apair of cutter elements, at least one of which is biased against saidanvil, and said punch also having a cutter element cooperativelyassociatcd with a cutter element of the die while being aligned with thesaid anvil of said die, the cutter element of the punch being providedwith a work-engaging surface which matches the configuration of thework-engaging surface on the anvil, the side edges of the cutter elementon the punch being angularly disposed in planes normal to thework-engaging surface of said last-mentioned cutter element and theWork-engaging surface of the cutter element on said punch and thework-engaging surface of the anvil on said die also being tapered inplanes normal to the said work-engaging surfaces of the said anvil andsaid last-mentioned cutter element whereby as the punch and die areclosed about overlapping pieces of material a portion of each piece ofmaterial will be displaced out of the respective normal planes thereofto effect a joint therebetween.

6. An apparatus as set forth in claim 5, wherein the Work-engagingsurfaces of the anvil and the cutter element on said punch havecooperating arcuate configur'ated portions.

7. In an apparatus for joining overlapping pieces of material togetherthe combination of a die and a punch, said die including a plurality ofanvils and cutter elements interdigitated with said anvils, at least oneof said anvils being provided with a generally arcuate Workengagingsurface, said punch also having a plurality of cutter elementscooperatively associated and aligned with the anvils on said die, thework-engaging surfaces of the cutter elements on said punch havingconfigurations which match the configurations of the work-engagingsurfaces on the anvils, and the side edges of the cutter elements on thepunch being angularly disposed in planes normal to the work-engagingsurfaces of said last-mentioned cutter elements, whereby as the punchand die are closed about the overlapping pieces of material a portion ofeach piece of material will be displaced out of the respective normalplane thereof to effect a joint therebetween.

8. An apparatus as set forth in claim 6 wherein the work-engagingsurfaces of the cutter elements on the punch and the work-engagingsurfaces of the anvils are tapered in planes normal to the work-engagingsurfaces of the anvil and the cutter elements on the punch.

9. An apparatus as set forth in claim 6 including means for removablyafiixing the cutter elements of the die to the anvils on the die andmeans for resiliently biasing certain of the cutter elements of the dieagainst the said anvils.

10. An apparatus as set forth in claim 6 including means for adjustingthe operating positions of the anvils of said die with respect to thecutter elements of said punch.

References Cited by the Applicant UNITED STATES PATENTS 12/1952Williams. 2/ 1960 Williams.

1. IN AN APPARATUS FOR JOINING OVERLAPPING PIECES OF MATERIAL TOGETHERTHE COMBINATION OF A DIE AND A PUNCH, SAID DIE INCLUDING AN ANVIL AND ATLEAST ONE CUTTER ELEMENT BIASED AGAINST SAID ANVIL, SAID ANVIL BEINGPROVIDED WITH A WORK-ENGAGING SURFACE, SAID PUNCH ALSO HAVING A CUTTERELEMENT COOPERATIVELY ASSOCIATED WITH THE CUTTER ELEMENT OF THE DIE ANDALIGNED WITH THE SAID ANVIL ON SAID DIE, THE CUTTER ELEMENT ON THE PUNCHBEING PROVIDED WITH A WORK-ENGAGING SURFACE WHICH MATCHES THECONFIGURATION OF THE WORK-ENGAGING SURFACE ON THE ANVIL AND THE SIDEEDGES OF THE CUTTER ELEMENT ON THE PUNCH BEING ANGULARLY DISPOSED INPLANES NORMAL TO THE WORK-ENGAGING SUR-